线段树的模板
1 #include<iostream> 2 #include<cstdio> 3 #include<cmath> 4 #include<algorithm> 5 #include<cctype> 6 #include<cstdlib> 7 #include<cstring> 8 9 using namespace std; 10 11 const int Maxn = 2e6 + 10; 12 int fa[Maxn]; 13 struct node 14 { 15 int l, r; 16 int value; 17 int mid() { 18 return (l + r) / 2; 19 } 20 }s[Maxn]; 21 void build(int i, int l, int r) 22 { 23 s[i].l = l; 24 s[i].r = r; 25 s[i].value = 0; 26 while (r == l) { 27 fa[l] = i; 28 return; 29 } 30 build(i * 2, l, (l + r) / 2); 31 build(i * 2 + 1, (l + r) / 2 + 1, r); 32 } 33 void updata(int x) 34 { 35 if (x == 1) return; 36 int fi = x / 2; 37 int a = s[fi * 2].value; 38 int b = s[fi * 2 + 1].value; 39 s[fi].value = max(a, b); 40 updata(fi); 41 } 42 int Max; 43 void query(int i, int l, int r) 44 { 45 if (s[i].l == l && s[i].r == r) { 46 Max = max(Max, s[i].value); 47 return; 48 } 49 int m = s[i].mid(); 50 if (r <= m) query(i << 1, l, r); 51 else if (l > m) query(i << 1 | 1, l, r); 52 else { 53 query(i << 1, l, m); 54 query(i << 1 | 1, m + 1, r); 55 } 56 57 } 58 int main() 59 { 60 int n, m; 61 while (scanf("%d %d", &n, &m) == 2) { 62 build(1, 1, n); 63 for (int i = 1;i <= n;i++) { 64 int x; 65 scanf("%d", &x); 66 s[fa[i]].value = x; 67 updata(fa[i]); 68 } 69 while (m--) { 70 char t[10]; 71 int a, b; 72 scanf("%s", t); 73 scanf("%d %d", &a, &b); 74 if (t[0] == 'Q') { 75 Max = 0; 76 query(1, a, b); 77 printf("%d ", Max); 78 } 79 else { 80 s[fa[a]].value = b; 81 updata(fa[a]); 82 } 83 } 84 } 85 return 0; 86 }